Review paper finds the so-called unprecedented warmth of the late 20th century (in China) is simply a myth
Review paper finds the so-called unprecedented warmth of the late 20th century is simply a myth
http://hockeyschtick.blogspot.com/2013/08/review-paper-finds-so-called.html
A new paper from SPPI and CO2 Science reviews the scientific literature on historical temperature trends in China and concludes, “the results of these several studies demonstrate that the so-called unprecedented warmth of the late 20th century is simply a myth, as far as China is concerned. The apparent great warmth of this period in this particular part of the world appears to have been but a common manifestation of naturally-induced and regularly-recurring conditions similar to those that have been experienced in prior millennia. These results also serve as a testimony against those who would deny the existence of an extensive (hemispheric or global) Medieval Warm Period and Little Ice Age, as well as an extensive Roman Warm Period and Dark Ages Cold Period, and cyclical climate changes in general.”
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[Illustrations, footnotes and references available in PDF version]
Controversy abounds over the temperature history of the earth, particularly that of the past one to two millennia. The original debate was sparked by the papers of Mann et al. (1998, 1999), which challenged the long-accepted view that there was nothing unusual about earth’s climatic history subsequent to the inception of the Industrial Revolution; and it prompted the Intergovernmental Panel on Climate Change (IPCC) to disavow their original representation of the temperature history of the Holocene (Houghton et al., 1990), where several periods of time prior to the inception of the Industrial Revolution were depicted as having experienced temperatures that were higher than those of the latter part of the 20th century.
For a considerable amount of time during the Medieval Warm Period, this large chunk of China enjoyed greater warmth than has yet to be experienced in modern times during the winter season.
The cyclical nature of the millennial-scale oscillation of climate that is evident in both climate records further suggests that there is no need to invoke rising atmospheric CO2 concentrations as a cause of the development of the Modern Warm Period.
From 1890 to 1950, another warm and dry period held sway, followed by a cooling since the end of the 1940s, which is at odds with the hockeystick temperature history of Mann et al. (1998, 1999).
In conclusion, the results of these several studies demonstrate that the so-called unprecedented warmth of …
New paper finds global carbon cycle datasets may be biased – Published in Global Biogeochemical Cycles
New paper finds global carbon cycle datasets may be biased
http://hockeyschtick.blogspot.com/2013/08/new-paper-finds-global-carbon-cycle.html
A paper published today in Global Biogeochemical Cycles finds prior calculations of the global carbon cycle may be erroneous because such calculations are based upon partial pressures of CO2 from several meters below the ocean surface instead of CO2 levels at the ocean surface [“the boundary layer”] where CO2 is actually exchanged between the atmosphere and ocean. The authors find a “strong” CO2 variability between the global datasets measured from several meters below the surface in comparison to the ocean surface that cannot be explained by Henry’s Law alone, and are primarily due to variations biological activity between these layers. The authors recommend, “Observations of pCO2 just beneath the air-sea boundary layer should be further investigated in order to estimate possible biases in calculating global air-sea CO2 fluxes.”Prevalence of strong vertical CO2 and O2 variability in the top meters of the oceanMaria Ll. Calleja et al
Abstract: The gradient in the partial pressure of carbon dioxide (pCO2) across the air-sea boundary layer is the main driving force for the air-sea CO2 flux. Global data-bases for surface seawater pCO2 are actually based on pCO2 measurements from several meters below the sea surface, assuming a homogeneous distribution between the diffusive boundary layer and the upper top meters of the ocean. Compiling vertical profiles of pCO2, Temperature and dissolved oxygen in the upper 5-8 meters of the ocean from different biogeographical areas, we detected a mean difference between the boundary layer and 5 m pCO2 of 13 ± 1 µatm. Temperature gradients accounted for only 11 % of this pCO2 gradient in the top meters of the ocean, thus, pointing to a heterogeneous biological activity underneath the air-sea boundary layer as the main factor controlling the top meters pCO2 variability. Observations of pCO2 just beneath the air-sea boundary layer should be further investigated in order to estimate possible biases in calculating global air-sea CO2 fluxes.
Related:
New paper finds ocean along N. California coast is a net source of CO2 to the atmosphere
New paper finds ocean along Baja California coast is a net source of CO2 to the atmosphere
New paper finds the oceans are a net source of CO2
Henry’s law – Wikipedia, the free encyclopedia
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Enviro-lawsuit forces five Indiana coal plants to shut down: ‘A lawsuit brought by environmental groups has forced the shutdown of five Indiana coal-fired power plants by 2018, totalling 668 megawatts of power’
Enviro-lawsuit forces five Indiana coal plants to shut down | The Daily Caller
http://dailycaller.com/2013/08/30/enviro-lawsuit-forces-five-indiana-coal-plants-to-shut-down/
The “war on coal” has five new casualties.
A lawsuit brought by environmental groups has forced the shutdown of five Indiana coal-fired power plants by 2018, totalling 668 megawatts of power.
Duke Energy announced that it would retire five coal plants as part of a settlement reached with the Sierra Club and other environmental groups in a dispute over a clean air permit Duke was issued by the state of Indiana for its new coal-gasification plant in the southwestern part of the state. The five plants will be retired by 2018.…
Observed Rate of Global Warming Half of What the Models Predict
Observed Rate of Global Warming Half of What the Models Predict
http://hockeyschtick.blogspot.com/2013/08/observed-rate-of-global-warming-half-of.html
Observed Rate of Global Warming Half of What the Models PredictRonald Bailey| Aug. 30, 2013 12:32 pm Reason.comThat’s what an interesting new article in Nature Climate Change points out. The article, “Overestimated warming over the past 20 years,” by members in good standing of the “climate community” compares model simulations from 37 of the climate models being used by the Intergovernmental Panel on Climate Change to project future temperatures with the actual global temperature increase over the past two decades. The study (since it’s behind a paywall I am linking to the version published online at the AGW skeptical website the Hockeyschtick) reports:
Global mean surface temperature over the past 20 years (1993–2012) rose at a rate of 0.14 ± 0.06 °C per decade (95% confidence interval)1. This rate of warming is significantly slower than that simulated by the climate models participating in Phase 5 of the Coupled Model Intercomparison Project (CMIP5). To illustrate this, we considered trends in global mean surface temperature computed from 117 simulations of the climate by 37 CMIP5 models. These models generally simulate natural variability — including that associated with the El Niño–Southern Oscillation and explosive volcanic eruptions — as well as estimate the combined response of climate to changes in greenhouse gas concentrations, aerosol abundance (of sulphate, black carbon and organic carbon, for example), ozone concentrations (tropospheric and stratospheric), land use (for example, deforestation) and solar variability. By averaging simulated temperatures only at locations where corresponding observations exist, we find an average simulated rise in global mean surface temperature of 0.30 ± 0.02 °C per decade (using 95% confidence intervals on the model average). The observed rate of warming given above is less than half of this simulated rate, and only a few simulations provide warming trends within the range of observational uncertainty… (emphasis added). …
The inconsistency between observed and simulated global warming is even more striking for temperature trends computed over the past fifteen years (1998–2012). For this period, the observed trend of 0.05 ± 0.08 °C per decade is more than four times smaller than the average simulated trend of 0.21 ± 0.03 °C per decade. It is worth noting that the observed trend over this period — not significantly different from zero — suggests a temporary ‘hiatus’ in global warming. (emphasis added).
The article concludes:
Ultimately the causes …